The subjects included in the ranking cover the study programmes of about 80% of all first-year students. The selection is done on the basis of the frequency in which the subjects are studied. The subjects not included are often offered by only a few HEIs, or have relatively few students enrolled per HEI. For the formation of the ranking groups on which the ranking is based, a minimum number of academic locations (about 20) is required. In addition, an appropriate number of students is required in order to get sufficient feedback for the student interviews. In addition, newly-created subjects have the additional problem of having minimal research indicators (e.g. doctorates, third party funds) to evaluate.